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Radoń M. Benchmarks for transition metal spin-state energetics: why and how to employ experimental reference data? Phys Chem Chem Phys 2023; 25:30800-30820. [PMID: 37938035 DOI: 10.1039/d3cp03537a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Accurate prediction of energy differences between alternative spin states of transition metal complexes is essential in computational (bio)inorganic chemistry-for example, in characterization of spin crossover materials and in the theoretical modeling of open-shell reaction mechanisms-but it remains one of the most compelling problems for quantum chemistry methods. A part of this challenge is to obtain reliable reference data for benchmark studies, as even the highest-level applicable methods are known to give divergent results. This Perspective discusses two possible approaches to method benchmarking for spin-state energetics: using either theoretically computed or experiment-derived reference data. With the focus on the latter approach, an extensive general review is provided for the available experimental data of spin-state energetics and their interpretations in the context of benchmark studies, targeting the possibility of back-correcting the vibrational effects and the influence of solvents or crystalline environments. With a growing amount of experience, these effects can be now not only qualitatively understood, but also quantitatively modeled, providing the way to derive nearly chemically accurate estimates of the electronic spin-state gaps to be used as benchmarks and advancing our understanding of the phenomena related to spin states in condensed phases.
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Affiliation(s)
- Mariusz Radoń
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Krakow, Poland.
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2
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Reimann M, Kaupp M. Reaction Entropies in Solution from Analytical Three-Dimensional Reference Interaction Site Model Derivatives with Application to Redox and Spin-Crossover Processes. J Phys Chem A 2022; 126:3708-3716. [PMID: 35652546 DOI: 10.1021/acs.jpca.2c02317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An analytical approach to compute the excess entropy of solvation at constant pressure in three-dimensional reference interaction site model (3D-RISM) calculations is presented. It includes the changes in the macroscopic dielectric constant of the solvent upon variation of temperature and density. The approach is exact within the framework of force-field descriptions of the solute and gives reasonable results for self-consistently determined electrostatics as used in the 3D-RISM-self-consistent field approach, particularly for entropy differences. The new method is applied to simple examples of reaction entropies of iron complexes in aqueous solution, for which simple gas-phase calculations and many other approaches give unreliable estimates. For both redox half-reactions and spin-crossover processes, (semi)quantitative agreement with experimental reaction entropies can be achieved out of the box.
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Affiliation(s)
- Marc Reimann
- Institut für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17.Juni 135, Berlin D-10623, Germany
| | - Martin Kaupp
- Institut für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17.Juni 135, Berlin D-10623, Germany
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3
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Livesay BN, Shores MP. Influence of Coordinated Triflate Anions on the Solution Magnetic Properties of a Neutral Iron(II) Complex. Inorg Chem 2021; 60:15445-15455. [PMID: 34596394 DOI: 10.1021/acs.inorgchem.1c02112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In an effort to probe the impacts of speciation on spin-state switching, the synthesis and unique solution-phase magnetic properties of [((TIPSC≡C)3tren)Fe(OTf)2] (1) are described. Analysis of the single-crystal X-ray diffraction data shows that the tris(iminoalkyne) ligand coordinates to the iron(II) center through all four nitrogen atoms, while the other two coordination sites are filled by the oxygen atoms from triflate anions. Solid-state variable-temperature (VT) magnetic studies show that 1 remains high-spin (HS) at all temperatures. In the presence of moderately strong coordinating solvents, solvent replaces the two bound triflate counteranions, as observed by 19F NMR spectroscopy and supported by conductivity measurements. VT solution measurements show 1 to be in the HS state when this solvent is oxygen-donating but low-spin (LS) with a nitrogen-donating solvent. In the noncoordinating solvent dichloromethane, both triflates are bound to the iron(II) center at room temperature, but upon cooling, 1 undergoes a coordination change, resulting in the loss of one triflate, as shown by 19F NMR. With the moderately coordinating solvent acetone, triflate dissociation upon cooling results in a spin-switching species with a T1/2 value of 171 K, characterized via 19F NMR, Evans' method, and solution magnetometry measurements. Solution magnetic measurements collected in structurally similar cyclopentanone suggest that the spin-state switching event is exclusive to the acetone environment, suggesting the influence of both the local coordination environment and aggregation. Additionally, a comparison of the solvodoynamic diameters via dynamic light scattering suggests that aggregation of 1 is significantly different in (CH3)2CO and (CD3)2CO, leading to the observation of spin-switching behavior in the former and fully HS behavior in the latter. This study highlights the sensitivity of solution magnetic properties to solvent choice.
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Affiliation(s)
- Brooke N Livesay
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Matthew P Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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4
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Connolly BJP, Brosius V, Mertes N, Demidova C, Bilyj JK, Riley MJ, Bernhardt PV. Temperature and Counterion Dependent Spin Crossover in a Hexaamineiron(II) Complex. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Blake J. P. Connolly
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Victor Brosius
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Nicole Mertes
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Caroline Demidova
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Jessica K. Bilyj
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Mark J. Riley
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
| | - Paul V. Bernhardt
- School of Chemistry and Molecular Biosciences University of Queensland Brisbane 4072 Australia
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5
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Bondì L, Rodríguez-Jiménez S, Feltham HLC, Garden AL, Brooker S. Probing the generality of spin crossover complex T½vs. ligand 15N NMR chemical shift correlations: towards predictable tuning. Inorg Chem Front 2021. [DOI: 10.1039/d1qi00919b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A study of 6 families (42 members) demonstrates that within a family the easily calculated 15N-NMR values of ligands enable predictable tuning of T1/2 in the corresponding complexes, except for 2 families with weakly influencing meta-substituents.
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Affiliation(s)
- Luca Bondì
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Department of Chemistry ‘Ugo Schiff’ and INSTM Research Unit, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Santiago Rodríguez-Jiménez
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Humphrey L. C. Feltham
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Anna L. Garden
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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6
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Singh S, Brooker S. Extension of Azine-Triazole Synthesis to Azole-Triazoles Reduces Ligand Field, Leading to Spin Crossover in Tris-L Fe(II). Inorg Chem 2020; 59:1265-1273. [PMID: 31909611 DOI: 10.1021/acs.inorgchem.9b02993] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first examples of azole-triazole Rat ligands, bidentate L4NMeIm(3-(1-methyl-1H-imidazol-4-yl)-5-phenyl-4-(p-tolyl)-4H-1,2,4-triazole) and L4SIm (4-(5-phenyl-4-(p-tolyl)-4H-1,2,4-triazol-3-yl)thiazole), have been prepared, by extension of the general synthesis used to access many examples of azine-triazoles. The tris-L FeII complexes of the azine-triazoles are consistently low spin (LS). As intended, these new azole-triazole ligands provide lower field strengths, resulting in high-spin (HS) [FeII(L4NMeIm)3](BF4)2 (1·4H2O) and spin crossover (SCO) active [FeII(L4SIm)3](BF4)2 (2·0.5H2O). Single-crystal structure determinations revealed that at 100 K 1·solvents is HS whereas 2·solvents is LS. Solid-state variable temperature magnetic studies of air-dried crystals showed that the methylimidazole-triazole complex 1·4H2O remains HS while the thiazole-triazole complex 2·0.5H2O undergoes a two-step gradual SCO (T1/2 approximately 275 and 350 K). Variable-temperature Evans method NMR studies of 2, in five different solvents (CD3NO2, CD3CN, CD3COCD3, CD2Cl2, and CDCl3) gave T1/2 values in a relatively narrow range, 214-259 K. These T1/2 values did not correlate with the solvent polarity index P' (R2 = 0.25) but did correlate with the solvent basicity parameter SB (R2 = 0.90). Variable-temperature UV-vis studies on a golden yellow CH3CN solution of 2, with monitoring of the d-d transition at 530 nm (ε = 39 L mol-1 cm-1 at 293 K) while the solution was heated from 253 to 303 K, showed that the high-spin fraction increased from 0.51 to 0.77. Cyclic voltammetry studies in CH3CN revealed a Fe(III)/Fe(II) redox process that was reversible for 1 and irreversible for 2, with significant tuning of the Epa value: the methylimidazole-triazole complex 1 is significantly easier to oxidize (0.46 V) than the thiazole-triazole complex 2 (0.68 V; both vs 0.01 M Ag/AgNO3).
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Affiliation(s)
- Sandhya Singh
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , PO Box 56, Dunedin 9054 , New Zealand
| | - Sally Brooker
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , PO Box 56, Dunedin 9054 , New Zealand
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7
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Sundaresan S, Kitchen JA, Brooker S. Hydrophobic tail length in spin crossover active iron( ii) complexes predictably tunes T½ in solution and enables surface immobilisation. Inorg Chem Front 2020. [DOI: 10.1039/c9qi01478k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Linear correlation of the hydrophobic alkyl tail length R employed in [FeII(LH-OR)(NCBH3)2] with the spin crossover switching temperature is a very convenient method of predictably tuning the iron(ii) spin state.
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Affiliation(s)
- Sriram Sundaresan
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology
- University of Otago
- Dunedin 9054
- New Zealand
| | - Jonathan A. Kitchen
- School of Natural and Computational Sciences
- Massey University Auckland
- New Zealand
| | - Sally Brooker
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology
- University of Otago
- Dunedin 9054
- New Zealand
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8
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Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties. MAGNETOCHEMISTRY 2019. [DOI: 10.3390/magnetochemistry5010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples that are based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K, whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K, as shown by thermogravimetric and DSC measurements.
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9
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McPherson JN, Hogue RW, Akogun FS, Bondì L, Luis ET, Price JR, Garden AL, Brooker S, Colbran SB. Predictable Substituent Control of Co III/II Redox Potential and Spin Crossover in Bis(dipyridylpyrrolide)cobalt Complexes. Inorg Chem 2019; 58:2218-2228. [PMID: 30672281 DOI: 10.1021/acs.inorgchem.8b03457] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A family of five easily prepared tridentate monoanionic 2,5-dipyridyl-3-(R1)-4-(R2)-pyrrolide anions (dppR1,R2)-, varying in the nature of the R1 and R2 substituents [R1, R2 = CN, Ph; CO2Et, CO2Et; CO2Me, 4-Py; CO2Me, Me; Me, Me], has been used to generate the analogous family of neutral [CoII(dppR1,R2)2] complexes, two of which are structurally characterized at both 100 and 298 K. Both the oxidation and spin states of these complexes can be switched in response to appropriate external stimuli. All complexes, except [CoII(dppMe,Me)2], exhibit gradual spin crossover (SCO) in the solid state, and SCO activity is observed for three complexes in CDCl3 solution. The cobalt(II) centers in the low spin (LS) complexes are Jahn-Teller tetragonally compressed along the pyrrolide-Co-pyrrolide axis. The complexes in their high spin (HS) states are more distorted than in the LS states, as is also usually the case for SCO active iron(II) complexes. The reversible CoIII/II redox potentials are predictably tuned by choice of substituents R1 and R2, from -0.95 (Me,Me) to -0.45 (CN,Ph) V vs Fc+/Fc, with a linear correlation observed between E1/2(CoIII/II) and the Swain-Lupton parameters of the pyrrolide substituents.
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Affiliation(s)
- James N McPherson
- School of Chemistry , The University of New South Wales , Kensington , NSW 2052 , Australia
| | - Ross W Hogue
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Folaranmi Sunday Akogun
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Luca Bondì
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Ena T Luis
- School of Chemistry , The University of New South Wales , Kensington , NSW 2052 , Australia
| | - Jason R Price
- ANSTO, Australian Synchrotron , Clayton , VIC Australia
| | - Anna L Garden
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Sally Brooker
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Stephen B Colbran
- School of Chemistry , The University of New South Wales , Kensington , NSW 2052 , Australia
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10
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Lee WT, Zeller M, Upp D, Politanska Y, Steinman D, Al-Assil T, Becker DP. Iron(II) complexes of dimethyltriazacyclophane. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2018; 74:1641-1649. [PMID: 30516148 DOI: 10.1107/s2053229618015255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/29/2018] [Indexed: 11/11/2022]
Abstract
Treatment of the ortho-triazacyclophane 1,4-dimethyltribenzo[b,e,h][1,4,7]triazacyclonona-2,5,8-triene [(C6H5)3(NH)(NCH3)2, L1] with Fe[N(SiMe3)2]2 yields the dimeric iron(II) complex bis(μ-1,4-dimethyltribenzo[b,e,h][1,4,7]triazacyclonona-2,5,8-trien-7-ido)bis[(μ-1,4-dimethyltribenzo[b,e,h][1,4,7]triazacyclonona-2,5,8-trien-7-ido)iron(II)], [Fe(C20H18N3)4] or Fe2(L1)4 (9). Dissolution of 9 in tetrahydrofuran (THF) results in solvation by two THF ligands and the formation of a simpler monoiron complex, namely bis(μ-1,4-dimethyltribenzo[b,e,h][1,4,7]triazacyclonona-2,5,8-trien-7-ido-κN7)bis(tetrahydrofuran-κO)iron(II), [Fe(C20H18N3)2(C4H8O)2] or (L1)2Fe(THF)2 (10). The reaction is reversible and 10 reverts in vacuo to diiron complex 9. In the structures of both 9 and 10, the monoanionic triazacyclophane ligand L1- is observed in only the less-symmetric saddle conformation. No bowl-shaped crown conformers are observed in the solid state, thus preventing chelating κ3-coordination to the metal as had been proposed earlier based on density functional theory (DFT) calculations. Instead, the L1- ligands are bound in either a η2-chelating fashion through the amide and one amine donor (for one of the four ligands of 9), or solely through their amide N atoms in an even simpler monodentate η1-coordination mode. Density functional calculations on dimer 9 revealed nearly full cationic charges on each Fe atom and no bonding interaction between the two metal centers, consistent with the relatively long Fe...Fe distance of 2.912 (1) Å observed in the solid state.
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Affiliation(s)
- Wei Tsung Lee
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 560 Oval Dr., W. Lafayette, IN 47907-2084, USA
| | - David Upp
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
| | - Yuliya Politanska
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
| | - Doug Steinman
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
| | - Talal Al-Assil
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
| | - Daniel P Becker
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan Road, Chicago, Illinois 60660, USA
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11
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Galadzhun I, Kulmaczewski R, Cespedes O, Yamada M, Yoshinari N, Konno T, Halcrow MA. 2,6-Bis(pyrazol-1-yl)pyridine-4-carboxylate Esters with Alkyl Chain Substituents and Their Iron(II) Complexes. Inorg Chem 2018; 57:13761-13771. [DOI: 10.1021/acs.inorgchem.8b02289] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iurii Galadzhun
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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12
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Hahn AW, Van Kuiken BE, Chilkuri VG, Levin N, Bill E, Weyhermüller T, Nicolaou A, Miyawaki J, Harada Y, DeBeer S. Probing the Valence Electronic Structure of Low-Spin Ferrous and Ferric Complexes Using 2p3d Resonant Inelastic X-ray Scattering (RIXS). Inorg Chem 2018; 57:9515-9530. [PMID: 30044087 DOI: 10.1021/acs.inorgchem.8b01550] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Understanding the detailed electronic structure of transition metal ions is essential in numerous areas of inorganic chemistry. In particular, the ability to map out the many particle d-d spectrum of a transition metal catalyst is key to understanding and predicting reactivity. However, from a practical perspective, there are often experimental limitations on the ability to determine the energetic ordering, and multiplicity of all the excited states. These limitations derive in part from parity and spin-selection rules, as well as from the limited energy range of many standard laboratory instruments. Herein, we demonstrate the ability of 2p3d resonant inelastic X-ray scattering (RIXS) to obtain detailed insights into the many particle spectrum of simple inorganic molecular iron complexes. The present study focuses on low-spin ferrous and ferric iron complexes, including [FeIII/II(tacn)2]3+/2+ and [FeIII/II(CN)6]3-/4-. This series thus allows us to assess the contribution of d-count and ligand donor type, by comparing the purely σ-donating tacn ligand to the π-accepting cyanide. In order to highlight the conceptual difference between RIXS and traditional optical spectroscopy, we compare first RIXS results with UV-vis and magnetic circular dichroism spectroscopy. We then highlight the ability of 2p3d RIXS to (1) separate d-d transitions from charge transfer transitions and (2) to determine the many particle d-d spectrum over a much wider energy range than is possible by optical spectroscopy. Our experimental results are correlated with semiempirical multiplet simulations and ab initio complete active space self-consistent field calculations in order to obtain detailed assignments of the excited states. These results show that Δ S = 1, and possibly Δ S = 2, transitions may be observed in 2p3d RIXS spectra. Hence, this methodology has great promise for future applications in all areas of transition metal inorganic chemistry.
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Affiliation(s)
- Anselm W Hahn
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Benjamin E Van Kuiken
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Vijay Gopal Chilkuri
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhem-Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Natalia Levin
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Thomas Weyhermüller
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Alessandro Nicolaou
- Synchrotron SOLEIL , L'Orme des Merisiers, Saint-Aubin , Boîte Postale 48, 91191 Gif-sur-Yvette Cedex, France
| | - Jun Miyawaki
- Institute for Solid State Physics (ISSP) , The University of Tokyo , Kashiwa , Chiba 277-8581 , Japan
| | - Yoshihisa Harada
- Institute for Solid State Physics (ISSP) , The University of Tokyo , Kashiwa , Chiba 277-8581 , Japan
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
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13
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Rodríguez-Jiménez S, Barltrop AS, White NG, Feltham HLC, Brooker S. Solvent Polarity Predictably Tunes Spin Crossover T1/2 in Isomeric Iron(II) Pyrimidine Triazoles. Inorg Chem 2018; 57:6266-6282. [PMID: 29767514 DOI: 10.1021/acs.inorgchem.8b00128] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Santiago Rodríguez-Jiménez
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Alexis S. Barltrop
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Nicholas G. White
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Humphrey L. C. Feltham
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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14
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Scott HS, Staniland RW, Kruger PE. Spin crossover in homoleptic Fe(II) imidazolylimine complexes. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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15
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Rodríguez-Jiménez S, Yang M, Stewart I, Garden AL, Brooker S. A Simple Method of Predicting Spin State in Solution. J Am Chem Soc 2017; 139:18392-18396. [DOI: 10.1021/jacs.7b11069] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Santiago Rodríguez-Jiménez
- Department of Chemistry and
MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Mingrui Yang
- Department of Chemistry and
MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Ian Stewart
- Department of Chemistry and
MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Anna L. Garden
- Department of Chemistry and
MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and
MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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16
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Rodríguez-Jiménez S, Brooker S. Solid Versus Solution Spin Crossover and the Importance of the Fe–N≡C(X) Angle. Inorg Chem 2017; 56:13697-13708. [PMID: 29112392 DOI: 10.1021/acs.inorgchem.7b01338] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Santiago Rodríguez-Jiménez
- Department of Chemistry and the MacDiarmid
Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and the MacDiarmid
Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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17
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Fatur SM, Shepard SG, Higgins RF, Shores MP, Damrauer NH. A Synthetically Tunable System To Control MLCT Excited-State Lifetimes and Spin States in Iron(II) Polypyridines. J Am Chem Soc 2017; 139:4493-4505. [DOI: 10.1021/jacs.7b00700] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Steven M. Fatur
- Department
of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Samuel G. Shepard
- Department
of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Robert F. Higgins
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Matthew P. Shores
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Niels H. Damrauer
- Department
of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
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18
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Thorarinsdottir AE, Gaudette AI, Harris TD. Spin-crossover and high-spin iron(ii) complexes as chemical shift 19F magnetic resonance thermometers. Chem Sci 2017; 8:2448-2456. [PMID: 28694955 PMCID: PMC5477811 DOI: 10.1039/c6sc04287b] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Accepted: 12/20/2016] [Indexed: 12/22/2022] Open
Abstract
The potential utility of paramagnetic transition metal complexes as chemical shift 19F magnetic resonance (MR) thermometers is demonstrated. Further, spin-crossover FeII complexes are shown to provide much higher temperature sensitivity than do the high-spin analogues, owing to the variation of spin state with temperature in the former complexes. This approach is illustrated through a series of FeII complexes supported by symmetrically and asymmetrically substituted 1,4,7-triazacyclononane ligand scaffolds bearing 3-fluoro-2-picolyl derivatives as pendent groups (L x ). Variable-temperature magnetic susceptibility measurements, in conjunction with UV-vis and NMR data, show thermally-induced spin-crossover for [Fe(L1)]2+ in H2O, with T1/2 = 52(1) °C. Conversely, [Fe(L2)]2+ remains high-spin in the temperature range 4-61 °C. Variable-temperature 19F NMR spectra reveal the chemical shifts of the complexes to exhibit a linear temperature dependence, with the two peaks of the spin-crossover complex providing temperature sensitivities of +0.52(1) and +0.45(1) ppm per °C in H2O. These values represent more than two-fold higher sensitivity than that afforded by the high-spin analogue, and ca. 40-fold higher sensitivity than diamagnetic perfluorocarbon-based thermometers. Finally, these complexes exhibit excellent stability in a physiological environment, as evidenced by 19F NMR spectra collected in fetal bovine serum.
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Affiliation(s)
- Agnes E Thorarinsdottir
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208-3113 , USA .
| | - Alexandra I Gaudette
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208-3113 , USA .
| | - T David Harris
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208-3113 , USA .
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19
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The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes. CRYSTALS 2016. [DOI: 10.3390/cryst6050058] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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20
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Hogue RW, Feltham HLC, Miller RG, Brooker S. Spin Crossover in Dinuclear N4S2 Iron(II) Thioether–Triazole Complexes: Access to [HS-HS], [HS-LS], and [LS-LS] States. Inorg Chem 2016; 55:4152-65. [DOI: 10.1021/acs.inorgchem.5b02851] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ross W. Hogue
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
PO Box 56, Dunedin 9054, New Zealand
| | - Humphrey L. C. Feltham
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
PO Box 56, Dunedin 9054, New Zealand
| | - Reece G. Miller
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
PO Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
PO Box 56, Dunedin 9054, New Zealand
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21
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Foscato M, Houghton BJ, Occhipinti G, Deeth RJ, Jensen VR. Ring Closure To Form Metal Chelates in 3D Fragment-Based de Novo Design. J Chem Inf Model 2015; 55:1844-56. [DOI: 10.1021/acs.jcim.5b00424] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Marco Foscato
- Department
of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
| | - Benjamin J. Houghton
- Inorganic
Computational Chemistry Group, Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, Great Britain
| | - Giovanni Occhipinti
- Department
of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
| | - Robert J. Deeth
- Inorganic
Computational Chemistry Group, Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, Great Britain
| | - Vidar R. Jensen
- Department
of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
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22
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Foscato M, Deeth RJ, Jensen VR. Integration of Ligand Field Molecular Mechanics in Tinker. J Chem Inf Model 2015; 55:1282-90. [DOI: 10.1021/acs.jcim.5b00098] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marco Foscato
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
| | - Robert J. Deeth
- Inorganic Computational
Chemistry Group, Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, Great Britain
| | - Vidar R. Jensen
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
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23
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Spin state behavior of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.08.006] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Houghton BJ, Deeth RJ. Spin-State Energetics of FeIIComplexes - The Continuing Voyage Through the Density Functional Minefield. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402253] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Barrett SA, Halcrow MA. Anion-dependent spin crossover in solution for an iron(ii) complex of a 1H-pyrazolyl ligand. RSC Adv 2014. [DOI: 10.1039/c4ra00230j] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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26
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SARDROODI JABERJAHANBIN, RASTKAR ALIREZA, YOUSEFNIA NEGARRAD, AZAMAT JAFAR. COMPARATIVE INVESTIGATION OF THE EFFECT OF TYPE OF DENSITY FUNCTIONAL IN THE DETERMINATION OF GEOMETRICAL PARAMETERS IN A Cu COMPLEX. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2013. [DOI: 10.1142/s0219633613500661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effects of short-range electron correlation, long-range electron exchange, local and nonlocal parts of density, higher order gradients of density, and adding some percentage of Hartree–Fock exchange to the functional on the prediction of geometrical parameters were investigated. A copper complex namely 1,2-bis(1,4,7-triaza-1-cyclononyl) ethane copper (II) with Jahn–Teller distortion in octahedral geometry was used to evaluate the performance of 50 commonly available density functionals. The standard 3-21G basis set was used for all light elements, while pseudo potential LANL2DZ was used for the copper atom. The best bond lengths and bond angles were obtained using M05-2x and OP functionals respectively. Also in order to more accurate survey the performance of B3LYP, we used this functional with two all-electron basis sets (6-31G and 3-21G) and three basis sets involving effective core potentials (LANL2DZ/3-21G, LANL2DZ, and LACVP).
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Affiliation(s)
- JABER JAHANBIN SARDROODI
- Molecular Simulations Laboratory, Azarbaijan Shahid Madani University, BP 5375171379 Tabriz, Iran
| | - ALIREZA RASTKAR
- Molecular Simulations Laboratory, Azarbaijan Shahid Madani University, BP 5375171379 Tabriz, Iran
| | - NEGAR RAD YOUSEFNIA
- Molecular Simulations Laboratory, Azarbaijan Shahid Madani University, BP 5375171379 Tabriz, Iran
| | - JAFAR AZAMAT
- Molecular Simulations Laboratory, Azarbaijan Shahid Madani University, BP 5375171379 Tabriz, Iran
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Kolanowski JL, Jeanneau E, Steinhoff R, Hasserodt J. Bispidine Platform Grants Full Control over Magnetic State of Ferrous Chelates in Water. Chemistry 2013; 19:8839-49. [DOI: 10.1002/chem.201300604] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Indexed: 11/11/2022]
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28
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Bilbeisi RA, Zarra S, Feltham HLC, Jameson GNL, Clegg JK, Brooker S, Nitschke JR. Guest Binding Subtly Influences Spin Crossover in an FeII4L4Capsule. Chemistry 2013; 19:8058-62. [DOI: 10.1002/chem.201300805] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Indexed: 11/08/2022]
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29
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Tolla AS, Banerjee A, Stjepanovic S, Li J, Brennessel WW, Loloee R, Chavez FA. Spin‐State Tuning in Iron(II) Triazamacrocyclic Complexes. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201201371] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Azam S. Tolla
- Department of Chemistry, Oakland University, Rochester, MI 48309‐4477, USA, Fax: +1‐248‐370‐2321, http://https://files.oakland.edu/users/chavez/web/Research.htm
| | - Atanu Banerjee
- Department of Chemistry, Oakland University, Rochester, MI 48309‐4477, USA, Fax: +1‐248‐370‐2321, http://https://files.oakland.edu/users/chavez/web/Research.htm
| | - Slavica Stjepanovic
- Department of Chemistry, Oakland University, Rochester, MI 48309‐4477, USA, Fax: +1‐248‐370‐2321, http://https://files.oakland.edu/users/chavez/web/Research.htm
| | - Jia Li
- Department of Chemistry, Oakland University, Rochester, MI 48309‐4477, USA, Fax: +1‐248‐370‐2321, http://https://files.oakland.edu/users/chavez/web/Research.htm
| | | | - Reza Loloee
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824‐1322, USA
| | - Ferman A. Chavez
- Department of Chemistry, Oakland University, Rochester, MI 48309‐4477, USA, Fax: +1‐248‐370‐2321, http://https://files.oakland.edu/users/chavez/web/Research.htm
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30
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Zlatar M, Gruden-Pavlović M, Güell M, Swart M. Computational study of the spin-state energies and UV-Visspectra of bis(1,4,7-triazacyclononane) complexes of some first-row transition metal cations. Phys Chem Chem Phys 2013; 15:6631-9. [DOI: 10.1039/c2cp43735j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Barrett SA, Kilner CA, Halcrow MA. Spin-crossover in [Fe(3-bpp)2][BF4]2 in different solvents – A dramatic stabilisation of the low-spin state in water. Dalton Trans 2011; 40:12021-4. [DOI: 10.1039/c1dt10620a] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Deeth RJ, Anastasi AE, Wilcockson MJ. An In Silico Design Tool for Fe(II) Spin Crossover and Light-Induced Excited Spin State-Trapped Complexes. J Am Chem Soc 2010; 132:6876-7. [DOI: 10.1021/ja1007323] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert J. Deeth
- Inorganic Computational Chemistry Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Anna E. Anastasi
- Inorganic Computational Chemistry Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Martin J. Wilcockson
- Inorganic Computational Chemistry Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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34
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Kuzu I, Krummenacher I, Hewitt I, Lan Y, Mereacre V, Powell AK, Höfer P, Harmer J, Breher F. Syntheses, Structures and Electronic Properties of Zwitterionic Iron(II) and Cobalt(II) Complexes Featuring Ambidentate Tris(pyrazolyl)methanide Ligands. Chemistry 2009; 15:4350-65. [DOI: 10.1002/chem.200802317] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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35
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Lord RL, Schultz FA, Baik MH. Spin Crossover-Coupled Electron Transfer of [M(tacn)2]3+/2+ Complexes (tacn = 1,4,7-Triazacyclononane; M = Cr, Mn, Fe, Co, Ni). J Am Chem Soc 2009; 131:6189-97. [DOI: 10.1021/ja809552p] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Richard L. Lord
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, and Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, Indiana 46402
| | - Franklin A. Schultz
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, and Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, Indiana 46402
| | - Mu-Hyun Baik
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, and Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, Indiana 46402
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36
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Mader EA, Manner VW, Markle TF, Wu A, Franz JA, Mayer JM. Trends in ground-state entropies for transition metal based hydrogen atom transfer reactions. J Am Chem Soc 2009; 131:4335-45. [PMID: 19275235 PMCID: PMC2723939 DOI: 10.1021/ja8081846] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors M(II)LH and oxyl radicals. [Fe(II)(H(2)bip)(3)](2+), [Fe(II)(H(2)bim)(3)](2+), [Co(II)(H(2)bim)(3)](2+), and Ru(II)(acac)(2)(py-imH) [H(2)bip = 2,2'-bi-1,4,5,6-tetrahydropyrimidine, H(2)bim = 2,2'-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2'-pyridyl)imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or (t)Bu(3)PhO(*) (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex M(III)L and TEMPOH or (t)Bu(3)PhOH. Solution equilibrium measurements for the reaction of [Co(II)(H(2)bim)(3)](2+) with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer, -41 +/- 2 cal mol(-1) K(-1). This is even more negative than the DeltaS(o)(HAT) = -30 +/- 2 cal mol(-1) K(-1) for the two iron complexes and the DeltaS(o)(HAT) for Ru(II)(acac)(2)(py-imH) + TEMPO, 4.9 +/- 1.1 cal mol(-1) K(-1), as reported earlier. Calorimetric measurements quantitatively confirm the enthalpy of reaction for [Fe(II)(H(2)bip)(3)](2+) + TEMPO, thus also confirming DeltaS(o)(HAT). Calorimetry on TEMPOH + (t)Bu(3)PhO(*) gives DeltaH(o)(HAT) = -11.2 +/- 0.5 kcal mol(-1) which matches the enthalpy predicted from the difference in literature solution BDEs. A brief evaluation of the literature thermochemistry of TEMPOH and (t)Bu(3)PhOH supports the common assumption that DeltaS(o)(HAT) approximately 0 for HAT reactions of organic and small gas-phase molecules. However, this assumption does not hold for transition metal based HAT reactions. The trend in magnitude of |DeltaS(o)(HAT)| for reactions with TEMPO, Ru(II)(acac)(2)(py-imH) << [Fe(II)(H(2)bip)(3)](2+) = [Fe(II)(H(2)bim)(3)](2+) < [Co(II)(H(2)bim)(3)](2+), is surprisingly well predicted by the trends for electron transfer half-reaction entropies, DeltaS(o)(ET), in aprotic solvents. This is because both DeltaS(o)(ET) and DeltaS(o)(HAT) have substantial contributions from vibrational entropy, which varies significantly with the metal center involved. The close connection between DeltaS(o)(HAT) and DeltaS(o)(ET) provides an important link between these two fields and provides a starting point from which to predict which HAT systems will have important ground-state entropy effects.
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Affiliation(s)
- Elizabeth A Mader
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA
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37
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Li QX, Wang XF, Cai L, Li Q, Meng XG, Xuan AG, Huang SY, Ai J. Crystal structure, superoxide dismutase activity and electrochemical property of complex [Cu(dtne)]·(ClO4)2·CH3CH2OH. INORG CHEM COMMUN 2009. [DOI: 10.1016/j.inoche.2008.11.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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38
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Hasegawa Y, Kume S, Nishihara H. Reversible light-induced magnetization change in an azobenzene-attached pyridylbenzimidazole complex of iron(ii) at room temperature. Dalton Trans 2009:280-4. [DOI: 10.1039/b817196n] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Halcrow MA. The spin-states and spin-transitions of mononuclear iron(II) complexes of nitrogen-donor ligands. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.03.033] [Citation(s) in RCA: 270] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Mader EA, Davidson ER, Mayer JM. Large ground-state entropy changes for hydrogen atom transfer reactions of iron complexes. J Am Chem Soc 2007; 129:5153-66. [PMID: 17402735 PMCID: PMC2628630 DOI: 10.1021/ja0686918] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reported herein are the hydrogen atom transfer (HAT) reactions of two closely related dicationic iron tris(alpha-diimine) complexes. FeII(H2bip) (iron(II) tris[2,2'-bi-1,4,5,6-tetrahydropyrimidine]diperchlorate) and FeII(H2bim) (iron(II) tris[2,2'-bi-2-imidazoline]diperchlorate) both transfer H* to TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) to yield the hydroxylamine, TEMPO-H, and the respective deprotonated iron(III) species, FeIII(Hbip) or FeIII(Hbim). The ground-state thermodynamic parameters in MeCN were determined for both systems using both static and kinetic measurements. For FeII(H2bip) + TEMPO, DeltaG degrees = -0.3 +/- 0.2 kcal mol-1, DeltaH degrees = -9.4 +/- 0.6 kcal mol-1, and DeltaS degrees = -30 +/- 2 cal mol-1 K-1. For FeII(H2bim) + TEMPO, DeltaG degrees = 5.0 +/- 0.2 kcal mol-1, DeltaH degrees = -4.1 +/- 0.9 kcal mol-1, and DeltaS degrees = -30 +/- 3 cal mol-1 K-1. The large entropy changes for these reactions, |TDeltaS degrees | = 9 kcal mol-1 at 298 K, are exceptions to the traditional assumption that DeltaS degrees approximately 0 for simple HAT reactions. Various studies indicate that hydrogen bonding, solvent effects, ion pairing, and iron spin equilibria do not make major contributions to the observed DeltaS degrees HAT. Instead, this effect arises primarily from changes in vibrational entropy upon oxidation of the iron center. Measurement of the electron-transfer half-reaction entropy, |DeltaS degrees Fe(H2bim)/ET| = 29 +/- 3 cal mol-1 K-1, is consistent with a vibrational origin. This conclusion is supported by UHF/6-31G* calculations on the simplified reaction [FeII(H2N=CHCH=NH2)2(H2bim)]2+...ONH2 left arrow over right arrow [FeII(H2N=CHCH=NH2)2(Hbim)]2+...HONH2. The discovery that DeltaS degrees HAT can deviate significantly from zero has important implications on the study of HAT and proton-coupled electron-transfer (PCET) reactions. For instance, these results indicate that free energies, rather than enthalpies, should be used to estimate the driving force for HAT when transition-metal centers are involved.
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Affiliation(s)
- Elizabeth A. Mader
- University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA, E-mail:
| | - Ernest R. Davidson
- University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA, E-mail:
| | - James M. Mayer
- University of Washington, Campus Box 351700, Seattle, WA, 98195-1700, USA, E-mail:
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41
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England J, Britovsek GJP, Rabadia N, White AJP. Ligand Topology Variations and the Importance of Ligand Field Strength in Non-Heme Iron Catalyzed Oxidations of Alkanes. Inorg Chem 2007; 46:3752-67. [PMID: 17411032 DOI: 10.1021/ic070062r] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of iron(II)-bis(triflate) complexes [Fe(L)(OTf)2] containing linear tetradentate bis(quinolyl)-diamine and bis(quinolylmethyl)-diamine ligands with a range of ligand backbones has been prepared. The coordination geometries of these complexes have been investigated in the solid state by X-ray crystallography and in solution by 1H and 19F NMR spectroscopy. Because of the labile nature of high-spin iron(II) complexes in solution, dynamic equilibria of complexes with different coordination geometries (cis-alpha, cis-beta, and trans) are observed with certain ligand systems. In these cases, the geometry observed in the solid-state does not necessarily represent the only or even the major geometry present in solution. The ligand field strength in the various complexes has been investigated by variable-temperature (VT) magnetic moment measurements and by UV-vis spectroscopy. The strongest ligand field is observed with the most rigid ligand that generates [Fe(L)(OTf)2] complexes with a cis-alpha coordination geometry, and the corresponding [Fe(L)(CH3CN)2]2+ complex displays spin crossover behavior. The catalytic properties of the complexes for the oxidation of cyclohexane have been investigated using hydrogen peroxide as the oxidant. An increased flexibility in the ligand results in a weaker ligand field, which increases the lability of the complexes. The activity and selectivity of the catalysts appear to be related to the strength of the ligand field and the stability of the catalyst.
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Affiliation(s)
- Jason England
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AY, United Kingdom
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Hossain F, Rigsby MA, Duncan CT, Milligan PL, Lord RL, Baik MH, Schultz FA. Synthesis, Structure, and Properties of Low-Spin Manganese(III)−Poly(pyrazolyl)borate Complexes. Inorg Chem 2007; 46:2596-603. [PMID: 17330969 DOI: 10.1021/ic062224+] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The manganese(III)-bis[poly(pyrazolyl)borate] complexes, Mn(pzb)2SbF6, where pzb- = tetrakis(pyrazolyl)borate (pzTp) (1), hydrotris(pyrazolyl)borate (Tp) (2), or hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) (3), have been synthesized by oxidation of the corresponding Mn(pzb)2 compounds with NOSbF6. The Mn(III) complexes are low-spin in solution and the solid state (microeff = 2.9-3.8 microB). X-ray crystallography confirms their uncommon low-spin character. The close conformity of mean Mn-N distances of 1.974(4), 1.984(5), and 1.996(4) A in 1, 2, and 3, respectively, indicates absence of the characteristic Jahn-Teller distortion of a high-spin d4 center. N-Mn-N bite angles of slightly less than 90 degrees within the facially coordinated pzb- ligands produce a small trigonal distortion and effective D3d symmetry in 1 and 2. These angles increase to 90.0(4)degrees in 3, yielding an almost perfectly octahedral disposition of N donors in Mn(Tp*)2+. Examination of structural data from 23 metal-bis(pzb) complexes reveals systematic changes within the metal-(pyrazolyl)borate framework as the ligand is changed from pzTp to Tp to Tp*. These deformations consist of significant increases in M-N-N, N-B-N, and N-N-B angles and a minimal increase in Mn-N distance as a consequence of the steric demands of the 3-methyl groups. Less effective overlap of pyrazole lone pairs with metal atom orbitals resulting from the M-N-N angular displacement is suggested to contribute to the lower ligand field strength of Tp* complexes. Mn(pzb)2+ complexes undergo electrochemical reduction and oxidation in CH3CN. The electrochemical rate constant (ks,h) for reduction of t2g4 Mn(pzb)2+ to t2g3eg2 Mn(pzb)2 (a coupled electron-transfer and spin-crossover reaction) is 1-2 orders of magnitude smaller than that for oxidation of t2g4 Mn(pzb)2+ to t2g3 Mn(pzb)22+. ks,h values decrease as Tp* > pzTp > Tp for the Mn(pzb)2+/0 electrode reactions, which contrasts with the behavior of the comparable Fe(pzb)2+/0 and Co(pzb)2+/0 couples.
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Affiliation(s)
- Ferdaus Hossain
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, Indiana 46202, USA
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Kobayashi M, Takashima A, Ishii T, Naka H, Uchiyama M, Yamaguchi K. Reverse Photochromic Behavior of an Iron−Magnesium Complex. Inorg Chem 2007; 46:1039-41. [PMID: 17256843 DOI: 10.1021/ic0616986] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have obtained a novel heterobimetallic iron-magnesium complex, (THF)4Mg(mu-Br)2FeBr2 (THF = tetrahydrofuran), which showed reverse photochromism in THF. The response exhibited in this system is associated with d-orbital splitting of the Fe atom and a change in the molecular aggregation state (dimerization).
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Affiliation(s)
- Minoru Kobayashi
- Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa 796-2193, Japan.
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Kolb JS, Thomson MD, Novosel M, Sénéchal-David K, Rivière É, Boillot ML, Roskos HG. Characterization of Fe(II) complexes exhibiting the ligand-driven light-induced spin-change effect using SQUID and magnetic circular dichroism. CR CHIM 2007. [DOI: 10.1016/j.crci.2006.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Bryliakov K, Duban E, Talsi E. The Nature of the Spin-State Variation of [FeII(BPMEN)(CH3CN)2](ClO4)2 in Solution. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400429] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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Coupled electron-transfer and spin-exchange reactions of metal–bis[tris(pyrazolyl)methane] complexes. Polyhedron 2004. [DOI: 10.1016/j.poly.2004.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cremer C, Burger P. Magnetic properties of cationic tungsten(IV) half sandwich compounds: experimental and theoretical study of a solvent and ligand stabilized singlet ground state leading to a thermally induced singlet-triplet spin state interconversion. J Am Chem Soc 2003; 125:7664-77. [PMID: 12812508 DOI: 10.1021/ja028313c] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of novel neutral tungsten(III) and cationic tungsten(IV) complexes with disubstituted 4,4'-R,R-2,2'-bipyridyl (R(2)-bpy) ligands of the type [CpW(R(2)-bpy)Cl(2)](n+) (n = 0,1) were prepared and characterized by X-ray crystallography. Susceptibility measurements of the tungsten(IV) complexes revealed an intrinsic paramagnetism of these compounds and evidenced different magnetic properties of the dimethylamino and methyl (R = NMe(2), Me) substituted tungsten(IV) compounds in solution and in the solid state. In dichloromethane solution, singlet ground states with thermally populated triplet states were observed, whereas triplet (R = Me) and singlet ground states (R = NMe(2)) were observed in the solid state. Using both experimental and theoretical techniques (DFT) allowed to establish solvation and ligand effects to account for the different magnetic behavior. Thermodynamic parameters were derived for the spin equlibria in solution by fits of the temperature dependent (1)H NMR shifts to the Van Vleck equation and were found to be in excellent agreement with the DFT calculations.
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Affiliation(s)
- Christian Cremer
- Anorg.-chem. Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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De Alwis DCL, Schultz FA. Metal-bis[poly(pyrazolyl)borate] complexes. Electrochemical, magnetic, and spectroscopic properties and coupled electron-transfer and spin-exchange reactions. Inorg Chem 2003; 42:3616-22. [PMID: 12767201 DOI: 10.1021/ic034077a] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrochemical, magnetic, and spectroscopic properties are reported for homoleptic divalent (M = Mn, Fe, Co, Ni, Ru) and trivalent (M = Cr, Mn, Fe, Co) metal-bis[poly(pyrazolyl)borate] complexes, [M(pzb)(2)](+/0), where pzb(-) = hydrotris(pyrazolyl)borate (Tp), hydrotris(3,5-dimethylpyrazolyl)borate (Tp), or tetrakis(pyrazolyl)borate (pzTp). Ligand field strengths in metal-pzb complexes increase as Tp < Tp < pzTp, which reflects the importance of steric rather than electronic effects on spectroscopic properties. However, metal-centered redox potentials become more negative as pzTp < Tp < Tp, which follows the electron-donating ability of the ligands. Co(III)/Co(II) and Mn(III)/Mn(II) electrode reactions are accompanied by a change in metal atom spin-state; i.e., (S = 0) [Co(pzb)(2)](+) + e(-) <==> (S = 3/2) [Co(pzb)(2)] and (S = 1) [Mn(pzb)(2)](+) + e(-) <==> (S = 5/2) [Mn(pzb)(2)]. Apparent heterogeneous electron-transfer rate constants derived from sweep-rate dependent cyclic voltammetric peak potential separations in 1,2-dichloroethane are small and decrease as pzTp > Tp > Tp for the Co(III)/Co(II) couples. Slow electron transfer is characteristic of coupled electron transfer and spin exchange. [M(Tp)(2)](+/0) redox potentials relative to values for other homoleptic MN(6)(3+/2+) couples change as M varies from Cr to Ni. For early members of the series, [M(Tp)(2)](+/0) potentials nearly equal those of complexes with aliphatic N-donor ligands (e.g., triazacyclononane, sarcophagine). However, [M(Tp)(2)](+/0) potentials approach those of [M(bpy)(3)](3+/2+) for later members of the series. The variation suggests a change in the nature of the metal-pzb interaction upon crossing the first transition row.
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Affiliation(s)
- D Chanaka L De Alwis
- Department of Chemistry, Indiana University Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, Indiana 46202-3274, USA
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Yoder JC, Roth JP, Gussenhoven EM, Larsen AS, Mayer JM. Electron and hydrogen-atom self-exchange reactions of iron and cobalt coordination complexes. J Am Chem Soc 2003; 125:2629-40. [PMID: 12603151 DOI: 10.1021/ja0273905] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reported here are self-exchange reactions between iron 2,2'-bi(tetrahydro)pyrimidine (H(2)bip) complexes and between cobalt 2,2'-biimidazoline (H(2)bim) complexes. The (1)H NMR resonances of [Fe(II)(H(2)bip)(3)](2+) are broadened upon addition of [Fe(III)(H(2)bip)(3)](3+), indicating that electron self-exchange occurs with k(Fe,e)(-) = (1.1 +/- 0.2) x 10(5) M(-1) s(-1) at 298 K in CD(3)CN. Similar studies of [Fe(II)(H(2)bip)(3)](2+) plus [Fe(III)(Hbip)(H(2)bip)(2)](2+) indicate that hydrogen-atom self-exchange (proton-coupled electron transfer) occurs with k(Fe,H.) = (1.1 +/- 0.2) x 10(4) M(-1) s(-1) under the same conditions. Both self-exchange reactions are faster at lower temperatures, showing small negative enthalpies of activation: DeltaH++(e(-)) = -2.1 +/- 0.5 kcal mol(-1) (288-320 K) and DeltaH++(H.) = -1.5 +/- 0.5 kcal mol(-1) (260-300 K). This behavior is concluded to be due to the faster reaction of the low-spin states of the iron complexes, which are depopulated as the temperature is raised. Below about 290 K, rate constants for electron self-exchange show the more normal decrease with temperature. There is a modest kinetic isotope effect on H-atom self-exchange of 1.6 +/- 0.5 at 298 K that is close to that seen previously for the fully high-spin iron biimidazoline complexes.(12) The difference in the measured activation parameters, E(a)(D) - E(a)(H), is -1.2 +/- 0.8 kcal mol(-1), appears to be inconsistent with a semiclassical view of the isotope effect, and suggests extensive tunneling. Reactions of [Co(H(2)bim)(3)](2+)-d(24) with [Co(H(2)bim)(3)](3+) or [Co(Hbim)(H(2)bim)(2)](2+) occur with scrambling of ligands indicating inner-sphere processes. The self-exchange rate constant for outer-sphere electron transfer between [Co(H(2)bim)(3)](2+) and [Co(H(2)bim)(3)](3+) is estimated to be 10(-)(6) M(-1) s(-1) by application of the Marcus cross relation. Similar application of the cross relation to H-atom transfer reactions indicates that self-exchange between [Co(H(2)bim)(3)](2+) and [Co(Hbim)(H(2)bim)(2)](2+) is also slow, < or =10(-3) M(-1) s(-1). The slow self-exchange rates for the cobalt complexes are apparently due to their interconverting high-spin [Co(II)(H(2)bim)(3)](2+) with low-spin Co(III) derivatives.
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Affiliation(s)
- Jeffrey C Yoder
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
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